Digital phonocardiography: a PDA-based approach

In this paper we demonstrate the applicability of advanced digital signal processing algorithms to the analysis of heart sound signals and describe the development of a PDA-based biomedical instrument capable of acquisition, processing, and analysis of heart sounds. Fourier transform-based spectral analysis of heart sounds was carried out first to show the differences in the frequency contents of normal and abnormal heart sounds. As the time-varying nature of heart sounds calls for better techniques capable of analyzing such signals: the short time Fourier transform (STFT) or spectrogram analysis was performed next. This method performed remarkably well in displaying frequency, magnitude, and time information of the heart sounds, providing robust parameters to make accurate diagnosis. With continuous technological advancements in computing and biomedical instrumentation, and the concurrent popularity of handheld instruments in the medical community, we introduce the concept of PDA-based digital phonocardiography. A prototype system is comprised of a digital stethoscope and a pocket PC. Heart sounds are recorded and displayed in the pocket PC screen. Advanced signal processing algorithms are implemented using the combined capabilities of software tools such as LabVlEW and embedded Visual C⁺⁺.